C 380 ) 
quorem refolutis, qu£ per fuos meatus i montiius 
fontium inftar fcaturit^ ac inde oleum petra diilum e(l^ qu$d 
videlicet ex petris profluat. This fpontaneous Accen/ion 
of the Naphtha feems to be made out by the Smell that 
our Bitumen near Edenlurgh yields , being moft like 
Coal-Smoak. There are three (iich Fires on the fame 
Hills that are extinguifht in the Summer, but burn in 
the Winter. The Reafbn of which I judge to be, that 
the Bowels of the Earth being cooler in Summer than in 
Winter, do not (end forth that Quantity of thofe fub- 
tile Exhalations as may be fufBcient to maintain a Flame 
in Summer ; but in Winter, the Bowels of the Earth be- 
ing hotter (which is made evident by the fmoakingof 
Springs in Winter, and not in Summer, and the Experi- 
ence of Miners) greater Plenty of Steams are fent forth, 
which in the Air are agitated into a Flame, the brisk of 
the Parts one againft another, being promoted by the 
fubtilty and brisk Motion of the Aerial Particles, qu£ 
mutuus dant operas. 
An eafy Contrivance of a Lamp to be h^pt always 
fnll whilfi it burns. 
SIR, 
MY writing of this Accenfion of combuftible Mat- 
ter by the Air, puts me in mind of your Obfer- 
vation about the Aftion of Flame, upon the Wyck of a 
Lamp or Candle, which it never waftes till the Wyck be 
expos'd to the Air by the Flames falling downwards, 
from which you infer, that a way found out to keep the 
Fuel, and confequently the Flame at the f^e height 
upon the Wyck, would make it ferve a long time ; for 
which effeding, you have a great many pretty Contri- 
vances. I have, a good while ago, thought the fame 
might 
